Tayammum

From one the two of them عليهما السلام, he said: When the traveler does not find water, then he is to look for it so long as he continues to be in the time (of the salat). So when he fears that the time will expire, then he is to do tayammum and pray.

The Messenger of Allah صلى الله عليه وآله said: I have been favored by four: The earth has been made a place of prostration for my nation (ummati), and any man from my nation who wants to pray and he has not found water but he has found earth, then it has been made a place of prostration for him and a purifier; I have been helped by terror (the distance of) a month’s journey; the spoils of war have been made lawful for my nation; and I have been sent to all of mankind.

Abu Ja`far عليه السلام was asked whether the man prays with a single wudu for all the salat of the night and day. He said: Yes, so long as he does not have a hadath. It was said to him: So does he pray with a single tayammum for all of the salat of the night and day so long as he does not have a hadath or comes in contact with water? He said: Yes. It was said: So if he comes in contact with water and hopes to be about to find other water, and he supposes that he will be able to (acquire) it whenever he wants it but that becomes difficult for him (i.e. he thought he would be able to find more water after, but was not able to)? He said: That breaks his tayammum and it is upon him to repeat the tayammum.